SpringBoot 1.x之使用Redis

以你之姓@ 2022-05-18 03:39 188阅读 0赞

在项目的pom.xml中引入以下依赖：

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
    </dependency>

配置：

#redis主机
    spring.redis.host=192.168.3.18

查看`RedisAutoConfiguration`源码：

@Configuration
    @ConditionalOnClass({RedisOperations.class})
    @EnableConfigurationProperties({RedisProperties.class})
    @Import({LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class})
    public class RedisAutoConfiguration { 
        public RedisAutoConfiguration() {
        }
    
        @Bean
        @ConditionalOnMissingBean(
            name = {
       "redisTemplate"}
        )
        public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
            RedisTemplate<Object, Object> template = new RedisTemplate();
            template.setConnectionFactory(redisConnectionFactory);
            return template;
        }
    
        @Bean
        @ConditionalOnMissingBean
        public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
            StringRedisTemplate template = new StringRedisTemplate();
            template.setConnectionFactory(redisConnectionFactory);
            return template;
        }
    }

可以看出为我们提供了`RedisTemplate`和`StringRedisTemplate`两个模板工具，用于简化对redis的操作。

`RedisTemplate`用于key-value的对象操作，而`StringRedisTemplate`偏向于字符串的操作

测试：  
这里就挑重点测试，其实这些模板的使用与命令行的命令是差不多的，类比就行。

一般将数据保存redis中，是以字符串的形式，即将其转化为json数据。

1.  自己将对象转成json数据，再以String-String的形式存入redis
2.  自定义RedisTemplate中的Serializer

这里不做设置，直接将其序列化存入redis中，注意：被序列化的对象需要实现Serializable接口

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class SpringBootCacheApplicationTests { 
    
        @Autowired
        private EmployeeMapper employeeMapper;
    
        @Autowired
        private StringRedisTemplate stringRedisTemplate;
    
        @Autowired
        private RedisTemplate redisTemplate;
    
        @Test
        public void testRedisTemplate(){
    
            Employee employee = employeeMapper.selectEmployeeById(1);
    
            redisTemplate.opsForHash().put("employee", employee.getId(), employee);
        }
    }

结果：  
![这里写图片描述][70]  
原因：  
在`RedisTemplate`中，默认的序列化器是`JdkSerializationRedisSerializer`

if (this.defaultSerializer == null) {
        this.defaultSerializer = new JdkSerializationRedisSerializer(this.classLoader != null ? this.classLoader : this.getClass().getClassLoader());
    }

而redis中的数据就是使用这个序列化器后的结果。

## 自定义模板组件以及序列化器： ##

@Configuration
    public class RedisConfig { 
    
        @Bean
        public RedisTemplate<Object, Employee> redisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
            RedisTemplate<Object, Employee> template = new RedisTemplate();
            template.setConnectionFactory(redisConnectionFactory);
    
            Jackson2JsonRedisSerializer<Employee> employeeJackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<Employee>(Employee.class);
    
            template.setDefaultSerializer(employeeJackson2JsonRedisSerializer);
    
            return template;
        }
    
    }

我们可以看到`RedisSerializer`的实现类：  
![这里写图片描述][70 1]  
选择`Jackson2JsonRedisSerializer`将其设置为默认的序列化器即可。

结果：  
![这里写图片描述][70 2]

接下来又有问题了，如果我们想存储的是别的表，而不是Employee呢？

我们可以通过自定义配置类加入多个自定义Template组件，分别由各自的CacheManager管理，使用的时候指定CacheManager就可以了。

@Configuration
    public class RedisConfig { 
    
        @Bean
        public RedisTemplate<Object, Employee> employeeRedisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
            RedisTemplate<Object, Employee> template = new RedisTemplate<Object, Employee>();
            template.setConnectionFactory(redisConnectionFactory);
            Jackson2JsonRedisSerializer<Employee> ser = new Jackson2JsonRedisSerializer<Employee>(Employee.class);
            template.setDefaultSerializer(ser);
            return template;
        }
        @Bean
        public RedisTemplate<Object, Department> departmentRedisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
            RedisTemplate<Object, Department> template = new RedisTemplate<Object, Department>();
            template.setConnectionFactory(redisConnectionFactory);
            Jackson2JsonRedisSerializer<Department> ser = new Jackson2JsonRedisSerializer<Department>(Department.class);
            template.setDefaultSerializer(ser);
            return template;
        }
    
        // 默认的CacheManger由RedisCacheConfiguration配置，其配置可参考RedisCacheConfiguration
        @Primary  // 作为默认的缓存管理器
        @Bean
        public RedisCacheManager employeeCacheManager(RedisTemplate<Object, Employee> employeeRedisTemplate){
            RedisCacheManager cacheManager = new RedisCacheManager(employeeRedisTemplate);
    
            //使用前缀，默认会将CacheName作为key的前缀
            cacheManager.setUsePrefix(true);
    
            return cacheManager;
        }
    
        @Bean
        public RedisCacheManager departmentCacheManager(RedisTemplate<Object, Department> departmentRedisTemplate){
            RedisCacheManager cacheManager = new RedisCacheManager(departmentRedisTemplate);
            cacheManager.setUsePrefix(true);
            return cacheManager;
        }
    }

使用：

@CacheConfig(cacheNames="employee", cacheManager="employeeCacheManager") // 抽取缓存的公共配置
    @Service
    public class EmployeeServiceImpl implements EmployeeService { 
    
        @Autowired
        EmployeeMapper employeeMapper;
    
        @Override
        @Cacheable()
        public Employee getEmployeeById(Integer id){
            Employee employee = employeeMapper.getEmployeeById(id);
            return employee;
        }
    }

@Service
    public class DepartmentServiceimpl implements DepartmentService { 
    
        @Autowired
        DepartmentMapper departmentMapper;
    
        @Autowired
        @Qualifier("departmentCacheManager")
        RedisCacheManager departmentCacheManager;
    
    // 1、使用注解缓存
    // @Override
    // @Cacheable(cacheNames = "department", cacheManager = "departmentCacheManager") // 指定cacheManager，获取相应的template
    // public Department getDepartmentById(Integer id){ 
    // Department department = departmentMapper.getDepartmentById(id);
    // return department;
    // }
    
    // 2、使用编码方式缓存
        // 使用缓存管理器得到缓存，进行api调用
        @Override
        public Department getDepartmentById(Integer id){
            Department department = departmentMapper.getDepartmentById(id);
    
            // 获取Cache
            Cache departmentCache = departmentCacheManager.getCache("department");
            departmentCache.put("department:"+department.getId(), department);
    
            return department;
        }
    }

[70]: /images/20220518/760179b4266e481fbab6896786f3bb20.png
[70 1]: /images/20220518/4553a9fd85924708aace43ffa138c7a3.png
[70 2]: /images/20220518/2f1417130fb3490a82c2a39aeeff1ef1.png